This invention relates to a process and composition for the administration of cytidyl diphosphocholine (CDP choline) that dissociates to form choline, along with a drug, in order to treat human disorders by increasing acetylcholine levels in brain and other tissues.
There are a number of diseases which affect acetylcholine-containing neurons in the brain or other tissues, and which are treated by drugs that cause undesired side effects by diminishing acetylcholine's release; there also exist diseases now treated by other drugs in which the potency and/or efficacy of the drugs could be improved by combining them with a source of choline in order thereby to enhance the release of acetylcholine. Such diseases include both those primarily involving the brain including diseases of higher cortical functions, psychiatric illnesses, movement disorders, old age, senility, Alzheimer's disease, Tardive dyskinesia, Parkinson's disease; certain affective disorders including mania, ataxias including Friedreich's ataxia, the dyslexias, the behavioral and neurological syndromes seen after brain trauma and/or anoxia, and those involving the peripheral nervous system, e.g., neuromuscular disorders such as myasthenia gravis as well as post stroke rehabilitation. Tardive dyskinesia, for example, is a particularly common movement disorder associated with inadequate release of brain acetylcholine as a result of drug administration for the initial brain disease (e.g., psychosis). Tardive dyskinesia is a choreic movement disorder characterized by involuntary twitches in the tongue, lips, jaw and extremities. It typically occurs in susceptible persons after chronic ingestion of neuroleptic drugs and may involve an imbalance in the postulated relation between dopaminergic and cholinergic neurons and the basal ganglions. Thus, drugs that either block catecholamine synthesis (e.g., alpha-methyl-p-tryosine), deplete the brain of monoamines (e.g., reserpine, tetrabenazine) or phenothiazines, haloperidol) often suppress tardive dyskinesia, whereas drugs that indirectly stimulate dopamine receptors (e.g. amphetamine, levodopa) often exacerbate the abnormal movements. Drugs assumed to increase the amount of acetylcholine within brain synapses (e.g., physostigmine, deanol), also tend to suppress the chorea of tardive dyskinesia, whereas anticholinergics (e. g., scopolamine), make it worse.
Not all choline analogues result in an increase in brain choline levels when administered to an animal. For example, deanol is a choline analogue which does not cause increased brain choline levels. However, when choline is administered by injection or by dietary supplementation increased blood choline levels in the rat results; this, in turn, increases choline levels in cholinergic neurons within the brain and elsewhere in the body, thereby accelerating the synthesis of acetylcholine, increasing tissue acetylcholine levels, and increasing the amounts of acetylcholine released into brain synapses. In human beings, oral doses of choline or of lecithin, a naturally-occurring compound that dissociates to choline, were found to cause dose-related increases in blood choline levels of sufficient magnitude (based on the studies on rats) to enhance brain acetylcholine synthesis and release; choline levels in the cerebrospinal fluid also rose in parallel. It has also been reported in four human patients that the administration of choline decreased the choreiform movements of tardive dyskinesia; no data were provided as to whether or not the drug given concurrently for psychosis (haloperidol, 3 mg per day) continued to be effective during the brief period of choline administration, and it was concluded that the apparent effectiveness of choline had to be interpreted with caution, since ". . . all four patients with tardive dyskinesia could have been gradually improving during the study" since this disease is characterized by extreme variability of clinical course. Thus, prior to this invention, it was known that choline and some choline analogues can be utilized to increase brain choline levels while other choline analogues do not result in increased brain choline levels.